Key switch assembly for electronic musical instruments

ABSTRACT

A key switch assembly for electronic musical instruments wherein there is mounted a printed circuit board close to the undersides of a row of parallel-arranged keys, the board being fitted with various circuit elements constituting a circuit for producing musical tones and also with a plurality of switch means operated by the corresponding key adjacent thereto through an actuator.

United States Patent Soprani. ..84/1.0l X

Ohno [4 1 June 20, 1972 [541 KEY SWITCH ASSEMBLY FOR 3,474,182 10/1969 ELECTRONIC MUSICAL 3.231.382 2; 137,11 INSTRUMENTS 2,497,113 1 2/1950 [72] Inventor: Junji Ohno, Hamamatsu, Japan 2,497,661 2/ 1950 2.555.040 5/1951 [73] Asslgnee: Nippon Gakki Seizo Kabushiki Kaisha, 2 933 004 4/1960 Hamamatsu-shi, Shizuoka-ken, Japan 3:060:784 10/1962 [22] Filed: June 30, 1970 3,068,334 12/1962 3,095,465 6/ 1963 PP 51,106 3,433,881 3/1969 3,5 76,958 5/1971 [30] Foreign Application Priority D. Primary Examiner-Lewis H. Myers July I, Japan Assistant Examinep-LL Weldon Attorney-Flynn 8!. Frishauf [52] U.S. Cl. ..84/L0l, 84/DIG. 7 [5|] lnt.Cl.'. ..Gl0h 1/00 57 ABSTRACT [58] Field ofSearch ..84/1.01, 1.24, 1.25 D, 423-425 A key switch assembly for electronic musical instruments wherein there is mounted a printed circuit board close to the [56] References Cited undersides of a row of parallel-arranged keys, the board being UNITED STATES PATENTS fitted with various circuit elements constituting a circuit for producing musical tones and also with a plurality of switch 3,536,819 10/1970 Kunyagawa et a1. ..84/l.01 means operated by the corresponding key adjacent thereto 3,335,629 8/1967 Brodin ...84/l,01 X through an actuaton 3,534,145 10/1970 Wfirl ...84/1.24 X 3,419,668 12/ l 968 3 China, 4 Drawing Figures P'ATENEDJum m2 sun-mar 4 1- II IIIIIIIIIIIII IIIIII VII/d.

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KEY SWITCH ASSEMBLY FOR ELECTRONIC MUSICAL INSTRUMENTS The present invention relates to electronic musical instruments and more particularly to a key switch assembly therefor including a printed circuit board with switch means and a circuitry disposed thereon to produce musical tones.

The prior art key switch assemblyof such kind often involves. interlocking multicircuit multicontact switch elements positioned right below the respective keys so as to control the generation of musical tones by being operatedthrough actuators, these switch elements being connected through a great number of lead wires to a circuitry associated with the production of musical tones which consists of, for example, tone generators and tone coloring filters. However, the greatest problem with the conventional key switch assembly is that the arrangement of lead wires is extremely complicated, and moreover they have to be manually set in place, not only requiring a great deal of time and labor with the resultant increased cost, but also, if there should occur errors in connection, necessitating much work and long hours in examination and repair.

Accordingly, the primary object of the present invention is to eliminate the aforementioned drawbacks, and prominently facilitate the assembly and manufacture of a key switch assembly for electronic musical instruments by employing] a printed circuit board with keyswitches and a circuitry disposed thereon for the generation of musical tones.

According to an aspect of the present invention, there is provided a key switch assembly for an electronic musical instrument which comprises a plurality of keys arranged parallel to each other, a plurality of actuators each provided for the respective key so as to be operated by depression of the corresponding key, a printed circuit board mounted under the keys, a plurality of switch means disposed on the printed circuit board, each switch means corresponding to the respective actuator and being actuated thereby, and a circuitry disposed on the printedcircuit board and electrically connected to said switch means for the production'of musical tones.

Further objects and advantages of the present invention will be apparent from the following description taken by reference to the appended drawings, in which:

FIG. 1 is a side view, partly in cross section, of a key switch assembly using a single set of keys embodying the present invention; and

FIGS. 2, 3 and 4 are, respectively, side views, partly in cross section, of key switch assemblies using two sets of keys embodying the invention. a

FIG. 1 represents a key switch assembly for an electronic musical instrument embodying the present invention which employs a single set of keys constituting one manual keyboard. On a key bed there is mounted a key frame 11 of metal plate, which carries at its rear end a vertical plate 12 supporting a plurality of keys 13 arranged parallel to-each other in a row. A coiled tension spring 14 is stretched between each key 13 and the lower end of the vertical plate 12 so as to bias the key front in an upward direction. The key frame 11 also carries at its front end a stopper piece 15 which limits the vertical movement of the keys 13. For each key 13 is provided an actuator 16 which is inserted into an aperture 17 formed in the horizontal portion of the frame 11. On that portion of the key bed 10 located under the keys 13 is mounted a printed circuit board 18 which extends across the entire row of keys 13. There is disposed on the printed circuit board 18 a plurality of switch means 19 and a plated or etched circuit pattern of a predetermined configuration and circuit elements such as integrated circuits 20 and resistors 21 which are required to form a circuitry involving, for example, tone generators,

frequency dividers and tone coloring filters. The circuit pattern connects electrically the switch means 19 and the circuit elements. The switch means 19 consists of a horizontally extending movable spring contact 22 normally urged upwards and a fixed contact 23 extending perpendicularly to the movable contact 22 at a predetermined space therefrom. Both the movable and fixed contacts 22 and 23 are fixedto a switch holder 24 mounted on the printed circuit board 18. The free end of the movable contact 22 is fitted to the lower end of the actuator 16. a

FIG. 2 illustrates another key switch assembly for an electronic musical. instrument embodying the present invention which employs two sets of keys constituting two manual keyboards, that is an upper set of keys 40 and a lower set of keys 41.. Both sets of keys 40 and 41 are mounted, respectively, on frames 42 and 43 in the same manner'as in the foregoing embodiment, and extend substantially in a horizontal direction. In this. embodiment, there is provided a single printed circuit board 44' positioned belowthe upper set of keys 40. The printed circuit board 44 is fixed to the frame 42 by means of a metal bracket 45 and extends vertically downwards from the frame 42 and also extends across the entire set of ,upper keys 40. As in the preceding embodiment, there is disposed on said printed circuit board 44 a plurality of switch means46 each consisting of two pairs of movable and fixed contacts both fixedly secured to the printed circuit board 44, and circuit elements such as integrated circuits 47 and re sistors 48, and a circuit pattemelectrically connecting the switch means 46 with the circuit elements. The circuit elements and the circuit pattern constitute a circuitry required for both the upper key switches and the lower key switches explained below. Each switchmeans 46 is actuated by an actuator 49 for the upper key 40.

For each of the lower keys 41 is provided a switch means 50 consisting of a pair of movable and fixed contacts and actuated by an actuator 51 for the lower key. The movable and fixed contacts of the switch means 50 are electrically connected to the printed circuit board 44 through lead wires 52.

FIG. .3 represents still another key switch assembly for an electronic musical instrument embodying the present invention which employs two upper and lower sets of keys, the sets of keys extending substantially in a horizontal direction. To a key bed 60 is fixed a printed circuit board 61 which is positioned under the upper and lower sets of keys 62 and 63 and horizontally extends across the entire sets of keys. At both ends of the printed circuit board 61 are disposed a plurality of switch means 64 for the upper keys 62 each consisting of two pairsof movable and fixed contacts, and a plurality of switch means 65 for the lower keys 63 each consisting of a pair of movable and fixed contacts, the switch means for the upper and lower keys being respectively actuated by actuators 66 and 67. On the intermediate portion of said board 61 between these switch means 64.and 65 are disposed circuit elements such as integrated circuits 68. and resistors 69, and a circuit pattern connecting between the switch means 64 and 65 and the circuit elements. Thus, a circuitry formed by the circuit elements and the circuit pattern may constitute tone generators, frequencydividers and tone coloring'filters.

FIG. 4 shows a different key switch assembly for an electronic musical instrument embodying the present invention which. employs two. sets of keys, that is, upper and lower sets of keys. This embodimentinvolves a printed circuit board 80 extending vertically downward from a frame 81 on which the upper sets of keys 82 are mounted, the board 80 being fixed to the frame 81 by means of a bracket 83. The printed circuit board 80 further extends across the entire sets of keys 82. At the upperand lower parts of the printed circuit board 80 are disposed a plurality of switch means 84 each corresponding to the respective upper key 82 and consisting of two pairs of movable and fixed contacts, and a plurality of switch means 85 each corresponding to the respective lower key 86 and consisting of a pair of movable and fixed contacts. Each switch means 84 positioned at the upper part of the printed circuit board is actuated by an upper key actuator 87 directly fixed to the movable contacts, whereas each switch means is actuated by the end of a lower key actuator 88 projecting from the rear end of the corresponding lower key 86. The

distance A between the fulcrum 89 of the upper key 82 and the upper key actuator 87 is made substantially equal to the distance B between the end of the lower key actuator 88 and the fulcrum 90 of the lower key 86, so that each movable contact for the upper and lower key switch means is allowed to start its contact with the corresponding fixed contact when each upper or lower key is depressed by the same distance.

In all embodiments shown above, the switch means are composed of movable contacts and fixed contacts, but are not restricted to only such combinations of contacts. The switch means may, as modified forms, be microswitches, reed switches, pressure-sensitive switches or magneto-sensitive switches.

According to the present invention, switch means are fitted to a printed circuit board and are electrically connected to circuit elements by means of a predetermined circuit pattern disposed on the printed circuit board, and, therefore, this makes it unnecessary to use a great number of lead wires to connect the switch means and the circuit elements, thus enhancing reliability of the key switch assembly and facilitating its manufacture and assembly and reducing the production cost to a great extent.

What is claimed is:

l. A key switch assembly for an electronic musical instrument which comprises:

at least upper and lower keyboards spaced from each other in a direction perpendicular to the planes of said keyboards and in offset relation to each other, each keyboard having a plurality of keys arranged in parallel to each other;

a plurality of actuators each provided for a respective key and coupled thereto so as to be operated by depression of said respective key;

a printed circuit board common to all of said keyboards, said common printed circuit board extending substan tially perpendicular to the planes of said keyboards, said common printed circuit board being mounted below the upper keyboard within the rear extremity of said upper keyboard and behind the lower keyboard;

a plurality of switch means selectively operated by the keys of said keyboards and all of said switch means being mounted on said common printed circuit board with the movable contacts thereof extending substantially perpendicularly from said common printed circuit board, each switch means corresponding to a respective actuator and being located to be actuated thereby upon depression of a key; and

a circuit disposed on said printed circuit board and electrically connected to all of said switch means by means of the printed circuits on said common printed circuit board for the production of musical tones upon depression of a key.

2. The key switch assembly as claimed in claim 1 wherein the keys of said two keyboards are pivotable on two different fulcrums, respectively; and said vertically extending printed circuit board is disposed between said two fulcrums; the distance between said fulcrum for said upper keyboard and a point at which said switch means for said upper keyboard are actuated by said actuators for said upper keyboard, is substantially equal to the distance between said fulcrum for said lower keyboard and a point at which said switch means for said lower keyboard are actuated by said actuators for said lower keyboard.

3. The key switch assembly as claimed in claim 2 wherein said actuators of said upper keyboard extend through respective apertures in said upper keyboard and are operated by said respective keys. 

1. A key switch assembly for an electronic musical instrument which comprises: at least upper and lower keyboards spaced from each other in a direction perpendicular to the planes of said keyboards and in offset relation to each other, each keyboard having a plurality of keys arranged in parallel to each other; a plurality of actuators each provided for a respective key and coupled thereto so as to be operated by depression of said respective key; a printed circuit board common to all of said keyboards, said common printed circuit board extending substantially perpendicular to the planes of said keyboards, said common printed circuit board being mounted below the upper keyboard within the rear extremity of said upper keyboard and behind the lower keyboard; a plurality of switch means selectively operated by the keys of said keyboards and all of said switch means being mounted on said common printed circuit board with the movable contacts thereof extending substantially perpendicUlarly from said common printed circuit board, each switch means corresponding to a respective actuator and being located to be actuated thereby upon depression of a key; and a circuit disposed on said printed circuit board and electrically connected to all of said switch means by means of the printed circuits on said common printed circuit board for the production of musical tones upon depression of a key.
 2. The key switch assembly as claimed in claim 1 wherein the keys of said two keyboards are pivotable on two different fulcrums, respectively; and said vertically extending printed circuit board is disposed between said two fulcrums; the distance between said fulcrum for said upper keyboard and a point at which said switch means for said upper keyboard are actuated by said actuators for said upper keyboard, is substantially equal to the distance between said fulcrum for said lower keyboard and a point at which said switch means for said lower keyboard are actuated by said actuators for said lower keyboard.
 3. The key switch assembly as claimed in claim 2 wherein said actuators of said upper keyboard extend through respective apertures in said upper keyboard and are operated by said respective keys. 